This application concerns an invention relating to vehicle fuel systems and particularly such a system which includes means to enhance or increase the fuel level with respect to a pump inlet particularly when the level in the fuel tank is relatively low, and also includes an alternate flow control to route fuel into the reservoir when blockage occurs in the primary level enhancing mechanisms.
Vehicles and particularly those with an internal combustion engine with a fuel injection system use a fuel pump to transport fuel from the fuel tank to the engine in quantities in excess of the engine needs under normal operating conditions. The excess fuel is returned to the fuel tank. It is desirable to provide a means in the fuel tank which will enhance or increase the fuel level surrounding a fuel pickup or fuel inlet. This fuel pickup may take the form of the inlet end of an in-tank electric fuel pump. In any case, when the level of fuel in the fuel tank drops to a relatively low level, say only one inch depth, it is desirable to provide means around the fuel pickup or inlet which will increase the level of fuel thereabout and with respect to the level in the remainder of the tank. Certain maneuvers of a vehicle will cause the fuel inlet to be uncovered and thus starve the fuel inlet or pickup. The resultant decrease of the already low fuel level may even cause engine malfunctions or stalling and particularly such problems with vehicles having a fuel injected engine.
Prior art disclosing a collector or reservoir assembly is disclosed in U.S. Pat. No. 4,397,333 to Liba and Rafferty which patent is assigned to Chrysler Corporation. In this patent, a small collector or reservoir is situated on the bottom of a fuel tank and encircles a fuel pickup or inlet of a fuel pump. An inlet tube near the bottom of the collector or reservoir assembly permits the flow of fuel therein from a fuel return line as well as from the surrounding fuel tank. The fuel from the return line is discharged at relatively high velocity into the open tube inlet of the reservoir. This jet action of fuel drags or induces fuel from the remainder of the tank into the reservoir or collector interior thus building up the fuel level therein with respect to the fuel level in the remainder of the tank. This type of fuel level enhancement may be characterized as jet aspiration owing to the effect of directing a high velocity flow of fuel into an open tube inlet to induce flow of additional quantities of fluid.
The fuel reservoir assembly described in the aforementioned patent has proven to operate successfully to produce significantly increased fuel levels with respect to the fuel inlet. However, if the conduit or return passage means for the excess fuel from the engine becomes blocked, the aforedescribed jet aspirator action ceases. Without the jet aspirator action, the fuel level within the cannister or reservoir will drop substantially. One cause of a blockage of return fuel could be the formation of ice around the outlet portion of the return line. Formation of ice is a result of water in the fuel. Water can be introduced to the fuel tank at a gas station in which the underground fuel tank has a leak or is not properly maintained so as to prevent accumulation of large quantities of water.
The subject improved fuel system includes a level enhancing reservoir or cannister in the fuel tank and also provides valved control means to insure a continuous return of fuel to the interior of the cannister or reservoir even if the jet aspirator outlet becomes clogged or otherwise blocked. Also, if the blockage is caused by the formation of ice at the outlet of the fuel return line, the resultant flow of excess fuel from the relatively warm engine compartment tends to unblock the outlet. Thus ice blockage of the jet outlet may be automatically melted.
Therefore, an advantage of the subject improved fuel and level enhancing system is its automatic functioning to ensure a continuous flow of return fuel to the reservoir to supply fuel for the inlet of the pump.
A further advantage of the system is the provision of valved flow control means normally supplying a primary flow of excess fuel through a jet aspirator to cause the fuel level in the cannister or reservoir to be increased with respect to fuel in the main part of the tank but including alternate flow means to ensure the continuous flow of the excess fuel even when the jet aspirator outlet may become blocked.
Other advantageous features of the subject application wil be obvious after a reading of the following detailed description of a preferred embodiment shown in the drawings described as follows.